Nowadays, severe uncertainty of electricity market price is a challenge issue in power systems that market players are faced. As one of market players, merchant compressed air energy storage system can be studied to investigate how energy is purchased/sold in the presence of electricity market price uncertainty. Therefore, this paper proposes, robust optimization approach is employed to achieve the offering and bidding curves of compressed air energy storage which should be submitted to the pool market. In the proposed method, the minimum and maximum amounts of electricity market prices are considered instead of the forecasted prices which allows formulating a collection of robust mixed-integer linear programming problem problems. The offering and bidding curves of compressed air energy storage are obtained based on sufficient data from results of these problems to be offered to the market operator. A case study is used to show the performance of proposed method. (C) 2017 Elsevier Ltd. All rights reserved.